The virtual reality technology VR refers to a technology that a three-dimensional environment is generated by means of a computer system and sensor technology, so as to create a novel human-machine interaction mode, so that a user enjoys a more realistic and immersive experience by senses such as vision, audition, touch and olfaction. The augmented reality technology AR is a technology that a position and an angle of a camera image are calculated in real time and a corresponding image, video and 3D model are integrated thereto, where an object of the technology is to embed a virtual world into the real world on a screen and interact with the virtual world.
Developments of the VR technology and the AR technology promote a video transmission rate and a video display quality. A video signal is transmitted between a signal source and a helmet display of a current split-type VR/AR device mainly via HDMI and DP. However, wires for traditional HDMI and DP are not lightweight enough, and extra two or three cables are required to transmit sensor signals and provide power and so on. Accordingly, the helmet device of the current split-type VR/AR tends to be very clunky and cannot provide good interaction performance for the user, thereby seriously affecting the experience of the user. Though there also are VR/AR products using wireless connection, due to rigid requirements on a data bandwidth, transmission delay, reliability and the like, the wireless connection of the VR/AR product, which has a low data rate at present and is susceptible to interference, tends to be limited in the field of the split-type VR/AR application.
USB Type-C is a newest USB interface formulated by the USB IF organization, has a capability of forward and reverse plugging and supplying high power, and can transmit multiple video protocols such as DP, HDMI and MHL. The USB Type-C interface can solve the problem of a large number of connection wires of a wire-connected head display device, and can simplify and expand a connection manner between a helmet and a host of the split-type VR/AR product. Multiple cables such as HDMI/DP and USB cables are not required any more, and only one USB Type-C cable can achieve video signal transmission in a higher resolution, provide a more real-time return signal of sensor data, and have a capability of supplying higher power online, and is more lightweight and portable for a terminal user. In addition to simple connection, a high resolution, a high refresh rate and supporting multiple video formats are also advantages of USB Type-C connection. With the USB Type-C, not only it is compatible with 4K30 Hz HDMI1.4b Alternate Mode, but also DP Alternate Mode with a data bandwidth up to 32.4 Gb/s is supported, thereby achieving 3D video transmission with 4K120 Hz or 8K60 Hz.
To provide an enough interaction movement space for the user, a long cable is usually used to connect the host and the helmet of the VR/AR device. However, for video transmission with a high resolution and a high data bandwidth, the long cable results in signal attenuation, thereby affecting a video quality, and causing the VR/AR device to fail to operate in serious conditions. Therefore, to improve a signal quality, it is usually required to add a Re-driver chip integrating an e-Marker function into the USB Type-C cable. In one aspect, a function of a passive EMCA is realized and identification information and various characteristics of the cable are provided to a USB Type-C source. In the other aspect, the attenuation of a high speed signal in the cable can be compensated and a transmission quality of a signal is improved. Such USB Type-C wire is referred to as an active EMCA. Usually, a signal of the Re-driver chip is transmitted in one direction, therefore, a data transmission direction of the cable is usually to be marked in the active EMCA provided with the Re-driver chip, and the cable is required to be connected strictly based on the data transmission direction. Accordingly, it not only results in inconvenience for the user using the VR/AR device, but also adds extra steps to mark the wire for production and manufacturing of the wire.
In summary, an urgent problem to be solved for those skilled in the art is how to solve the problem that it is required to connect a VR/AR device strictly based on the signal transmission direction of the Re-driver chip in a case that the VR/AR device is connected by the active EMCA.